Electric heater



F. E. FINLAYSON 2,269,194

ELIECTRIC HEATER Jan. 6, 1942.

Filed Dec. 19, 1939 MElflL/C MAM/50MB- rze/wmu Mus/ms Inventor: Fran k E. Fin layson,

His Attorney.

Patented Jan. 6, 1942 suac'rarc manna Frank EJFinlarson, Ontario, Calii'., assignor to General Electric Company, a corporation of New York H Application December 19, 1939, some No. 310,022;

8 Claims.

This invention relates to electric heaters, more particularly to electric heaters of the sheathwire type, and it has for its object the provision of improved means for sealing the terminals of heaters of this type.

Although not limited thereto, this invention has particular application in the sheathed heaterrdescribed in the United States Patent No. 1,367,341 to C. C..Abbott, dated February 1. 1921.

' As there described, this heater comprises a resistance conductor mounted in a metallic sheath, and supported in spaced relation with the sheath by a highly compacted mass of electrically insuvision of improved sealing means constructed and arranged so that the sealing means may be readily partially disassembled to provide for re-' placement of supply leads or to make any other needed repairs at the terminals.

In accordance with this invention, a suitable terminal housing is provided for each terminal. The housing has'one end surrounding the terminal end of the sheath, and it is so proportioned that it has a wall spaced from the outer wall or the sheath. Within the space between the sheath and the housing is a compacted mass of packing, which preferably will be graphite-impregnated asbestos. In one form of this invention, the packing is pressed betweenan inturned flange or abutment on the housing that flts closely about the sheath and an out-turned flange or abutment at the end of the sheath and which flts closely the inner wall of the terminal housingf and in this form of the invention, the two abutments or flanges are drawn toward each dther to highly compress the packing. Here alsofthe two abutments are drawn together by means of a loading plug which is fitted in the outer end of the terminal housing and is moved inwardly with reference to the terminal housing against a suitable loading member within.the housing to draw the housing outwardly and thereby move the two abutments together to highly compress fluid-impervious joint between the inner end of the terminal housing'and the sheath. A suitable electrical supply lead enters the housing through the packing plug, and preferably interposed between the plug and the loading member is a resilient ring surrounding the lead. This yieldable ring when the plug is forced inwardly of the housing is tightly wedged between the walls of the housing and the lead so as to provide a fluid-impervious joint at this point. The conducting member or the lead is securedto the terminal by soft solder or some similar means which upon heating to a relatively low temperature will permit dis-engagement of these members. And preferably, the plug will have a screw-threaded connection with the housing so that it may be forced inwardly by turning. Also, the parts may be disassembled merely by turning the plug to move it outwardly.

For a more complete understanding of this invention, reference, should be had to the accompanying drawing in which the single figure is an elevation mainly in section illustrating an electric-sheathed heater provided with terminal sealing means arranged in accordance with this invention.

Referring to the drawing, this invention has been'shown as applied to a sheathed electric supported in spaced relation with respect to the sheath by a highly compacted mass of electrically insulating and heat conducting material II. The material I! preferably will be granular magnesium oxide. Secured to the opposite ends of the resistance conductor I II are terminals I! (only one shown) which have their inner ends embedded in the mass [2 and their outer ends projecting from the sheath, as shown.

A suitable electrical supply lead I is provided for each terminal having a conductor core I! and an insulating covering it for the core. A connector I'I functions to connect the terminal I 3 with the conductor core l5. This member, as

shown, is of sleeve-like form, and has a centrallyarranged aperture receiving the projecting end of the terminal. Preferably, the sleeve I1 is brazed to the terminal, an opening it being provided in the sleeve through which the brazing 1 material I9 is inserted. The'core I! also is inthe packing. The asbestos packing provides a 55 connected with the connector by a soft or low temperature solder indicated by the numeral 20. Preferably, the connector at the lead endwill be provided with an outwardly extending flange 2| which iunctions as an abutment for the adjacent edge of the insulating covering IS.

A suitable terminal housing 22 is provided to house the pro e ing terminal, the inner end of the lead and the connection means between the terminal and lead. This housing, as shown, is

of tubular form, and has an internaldiameter somewhat larger than the external diameter of the sheath. The inner end of this housing surrounds the terminal end of the sheath, and it is provided with an inturned flange or. abutment 220 which flts the outer walls of the sheath relatively closely. The sheath has its terminal end provided with a spunout part 28 against which a suitable metal ring 2| bears. The metal ring 24 constitutes a second abutment or flange which extends outwardly and closely flts the inner wall oi the terminal housing. Interposed between the abutments or flanges 22a and 24 is a highly compacted mass of packing 25. Preferably, as-

bestos-impregnated with graphite will be used is 'provided with a centrally arranged aperture athrough which the lead is inserted. The plug works against a loading sleeve 21 formed of in the manner previously described, and after this, the loading sleeve 21 will be placed within the housing, and over this will be placed the yielding ring 30 and the metallic washer 3|. Then the plug 28 maybe screwed inwardly to compress the packing 26 and 30. If it is desired to gain access to the terminal or the connection means between the terminal and lead it is merely necessary to unscrew the plug 26 and slide the housing 22 inwardly of the sheath. 1! it be desired to replace the-lead it is merely necessary to heat the low temperature solder 20 to its melting point whereupon the lead may be withdrawn.

The graphite in the packing 25 i'unctions as a filler to prevent the asbestos from absorbing fluids. Also it providesior easy sliding movement of the housing 22 onthe sheath II.

.It will be observed that the sealing means of this invention is of simple and inexpensive construction, and is very easy to assemble and dis assemble.

.While I have shown a particular embodiment of my invention, it will be understood, 0! course. that I do not wish to be limited thereto since many modifications may be made and I, therefore, contemplate by .the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric heater comprising a conductor,

a sheath housing said conductor, a terminal for saidi conductor projecting from said sheath, a

any suitable electrically insulating material, such as',a suitable fiber having considerable mechani-' cal strength. The flber sleeve at its inner endabuts against an electrically insulating plate 2| which preferably will be formed or mica; as-

lead for said terminal, means connecting said lead with said terminal, a housing for said terminal and connecting means, said housing having a section surrounding the end portion of said sheath that is larger than said end portion so as shown, the plate 20 covers the end of the sheath,

its spun-out end 28 and also the metallic ring 24."

If desired and it is preferable to do so, a second plate 28 0i mica will be inserted in the sheath in the spun-out end section 28 immediately behindthe plate 28 so as to cover thei'exposed insulating mass l2. Interposed' between the inner end of the plug 26 and the outer end voi the loading sleeve 21 is a yieldable ring ill formed of any suitable yieldable material, such as rubber, and also ametallic loading plate 8| bearing on this ring and which is adapted to be engaged'directly by the inner end oi the plug 26,

t as shown. It will be observed that when the -At the same .time, '-it will highly compress the yielding ring II to-force it inwardly and out wardly against the and inner wall of the housing 22. The packing .25 and the ring 8! effect fluid impervious joint: between the terminal housing and the sheath and between the terminal housing and the lead I4. Preferably, V

the ring or washer it will have a concave surface 32 which centers the yielding ring 30 and prevents the flow' of the rubber upwardly between the inner and outer edges of the ring and the lead I4 and housing 22 respectively.

In assembling the sealing means, it will be understood that beforethe spun-out end 23 is formed on th sheath, the housing 22, the packing 25 and the metallic ring 24 all will be assembled with the sheath. Then the spun-out section 23 may be formed and the plates 28 and 2! assembled with the terminal l3. Thereafter, the lead it will be connected with the terminal I3 4 in leave a space between them, said sheath having an outwardly extending abutment at its end and said housing having an inwardly extending abutment on its inner end that has a sliding fit with said sheath, and a yieldable mass of packing in said space tightly compressed between said abutment'sso as to eifect a fluid-tight joint between said sheath and said-housing.

2. An electric heater comprising a conductor, a sheath housing said conductor, a terminal for said conductor projecting from said sheath, a lead for said terminal, means connecting said lead with said terminal, a housing for said terminal. and connecting means, said housing having a section surrounding the end portion of said sheath that is larger than said end portion so as to leave a space between them, the sheath having an outwardly extending abutment at its end and said housing having an inwardly extending abutment on its inner end, a yieldable mass of packing in said space, a plug threaded in said housing around said lead and turned inwardly to draw the two abutments tolead with said terminal, a housing for said terminal and" connecting means, said housing having a section' surrounding the end portion oi said sheath that is larger than said end portion so as to leave an annular space between the housing conductor proiecting irom said minal abutting said insulating member, a yield-.

said yieldable packing between said abutments and also .to force said packing ring against said loading sleeve to highly compress it against said lead, said loadingsleeve functioning to take the load of said plug as it is turned in.

i-ii'An electric heater comprising a conductor. a sheath housing said conductor, a terminal for said conductor projecting from said sheath, a lead for said terminal, means connecting said lead with said terminal. a housing for said terminal and connecting means, said housing having a section surrounding the end portion of said sheath that is larger than said portion so as to leave a space between them,

the sheath having an outwardly extending abutmentat its end and said housing having an inwardly extending abutment at its inner end engaging said sheath with a sliding flt, and a having an outwardly extending abutment at its outer end, yieldable packing between said abutment and said intumed inner end, an electrically insulating member threaded on said terminal so as to cover said sheath and said abutment, a loading sleeve within said housing around said terable ring'in said sleeve around said lead abutting said loading sleeve, and a loading plug around said lead forced in'the outer end of said housing to draw said inturned end toward said abutment and thereby highly compress said yieldable packing between them, and also to force said packing :ring against said loading sleeve and thereby tightly compress it between said lead and terminal housing.

7. An electric heater comprising a conductor, a sheath housing said conductor, a terminal for said conductor projecting from said sheath, a

mass oi graphite-impregnated asbestos in said space highly compressed between said abutments andthe walls 0! said sheath and housing.

5. An electric heater comprising a conductor,

a sheath housing said conductor, a terminal for said conductor projecting tromsaid sheath, a lead for said terminal, means connecting said lead with said terminal, a housing for said termi-' naland connecting means, said housing having a section surrounding the end portion of said, sheath that is larger than said end portion so as to leave a space between them, the housing having at its inner end an inwardly extending abutsaid lead and bearing against said sleeve, a plug around said lead threaded in said housing against housing for said terminal, said housing having asection surrounding the end portion or said sheath that is larger than said end portion so as to leave a space between them. the sheath having an outwardly extending abutment at its end and e said housing having an inwardly extending abutment on its inner end, said latter abutment having a sliding flt -with said sheath, a yieldable mass of packing in said space. a loading sleeve within said housing, a lead for said terminal entering said housing, a yieldable packing around said packing around the lead to highly compress it against said loading sleeve and said lead and to draw said abutments together and thereby highly compress said yieldable mass of packing, a connector secured to said terminal, and a sort.

. lowtemperature solder connecting said connecment and the sheath having a flanged-out part at its end, ametallic ring against said part, and a yieldable mass of packing in said space tightly compressed between said abutment and said ring. 6. An electric heater comprising asheath and aconductor in said sheath, a terminal for said sheath, a terminal housing for said terminal. a lead entering said housing and connected with said terminal, the housing having aninturnedinner end'that hasa slidingiitwithsaidsheath. andthesheath for relatively easy them.

tor with the conducting member of said lead.

, 8. An electric heater comprising a conductor, a metallic sheath housing said conductor. a terminal for said conductor projecting from one end 0! said sheath. a terminal housing for said ter.

minal having one end surrounding said end of said sheath in spaced relation-with it. and

graphite-impregnated asbestos packing interposedwithinthespacebetweensaidendotsaid sheathand said housing to provide a fluid-impervious Joint between them. and also. to provide sliding movement between mam: a. marson. 

